/*
 *  textbox.c -- implements the text box
 *
 *  ORIGINAL AUTHOR: Savio Lam (lam836@cs.cuhk.hk)
 *  MODIFIED FOR LINUX KERNEL CONFIG BY: William Roadcap (roadcap@cfw.com)
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "dialog.h"

static void back_lines (int n);
static void print_page (WINDOW * win, int height, int width);
static void print_line (WINDOW * win, int row, int width);
static char *get_line (void);
static void print_position (WINDOW * win, int height, int width);

static int hscroll = 0, fd, file_size, bytes_read;
static int begin_reached = 1, end_reached = 0, page_length;
static char *buf, *page;

/*
 * Display text from a file in a dialog box.
 */
int
dialog_textbox (const char *title, const char *file, int height, int width)
{
    int i, x, y, cur_x, cur_y, fpos, key = 0;
    int passed_end;
    char search_term[MAX_LEN + 1];
    WINDOW *dialog, *text;

    search_term[0] = '\0';    /* no search term entered yet */

    /* Open input file for reading */
    if ((fd = open (file, O_RDONLY)) == -1) {
    endwin ();
    fprintf (stderr,
         "\nCan't open input file in dialog_textbox().\n");
    exit (-1);
    }
    /* Get file size. Actually, 'file_size' is the real file size - 1,
       since it's only the last byte offset from the beginning */
    if ((file_size = lseek (fd, 0, SEEK_END)) == -1) {
    endwin ();
    fprintf (stderr, "\nError getting file size in dialog_textbox().\n");
    exit (-1);
    }
    /* Restore file pointer to beginning of file after getting file size */
    if (lseek (fd, 0, SEEK_SET) == -1) {
    endwin ();
    fprintf (stderr, "\nError moving file pointer in dialog_textbox().\n");
    exit (-1);
    }
    /* Allocate space for read buffer */
    if ((buf = malloc (BUF_SIZE + 1)) == NULL) {
    endwin ();
    fprintf (stderr, "\nCan't allocate memory in dialog_textbox().\n");
    exit (-1);
    }
    if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
    endwin ();
    fprintf (stderr, "\nError reading file in dialog_textbox().\n");
    exit (-1);
    }
    buf[bytes_read] = '\0';    /* mark end of valid data */
    page = buf;            /* page is pointer to start of page to be displayed */

    /* center dialog box on screen */
    x = (COLS - width) / 2;
    y = (LINES - height) / 2;


    draw_shadow (stdscr, y, x, height, width);

    dialog = newwin (height, width, y, x);
    keypad (dialog, TRUE);

    /* Create window for text region, used for scrolling text */
    text = subwin (dialog, height - 4, width - 2, y + 1, x + 1);
    wattrset (text, dialog_attr);
    wbkgdset (text, dialog_attr & A_COLOR);

    keypad (text, TRUE);

    /* register the new window, along with its borders */
    draw_box (dialog, 0, 0, height, width, dialog_attr, border_attr);

    wattrset (dialog, border_attr);
    mvwaddch (dialog, height-3, 0, ACS_LTEE);
    for (i = 0; i < width - 2; i++)
    waddch (dialog, ACS_HLINE);
    wattrset (dialog, dialog_attr);
    wbkgdset (dialog, dialog_attr & A_COLOR);
    waddch (dialog, ACS_RTEE);

    if (title != NULL && strlen(title) >= width-2 ) {
    /* truncate long title -- mec */
    char * title2 = malloc(width-2+1);
    memcpy( title2, title, width-2 );
    title2[width-2] = '\0';
    title = title2;
    }

    if (title != NULL) {
    wattrset (dialog, title_attr);
    mvwaddch (dialog, 0, (width - strlen(title))/2 - 1, ' ');
    waddstr (dialog, (char *)title);
    waddch (dialog, ' ');
    }
    print_button (dialog, " Exit ", height - 2, width / 2 - 4, TRUE);
    wnoutrefresh (dialog);
    getyx (dialog, cur_y, cur_x);    /* Save cursor position */

    /* Print first page of text */
    attr_clear (text, height - 4, width - 2, dialog_attr);
    print_page (text, height - 4, width - 2);
    print_position (dialog, height, width);
    wmove (dialog, cur_y, cur_x);    /* Restore cursor position */
    wrefresh (dialog);

    while ((key != ESC) && (key != '\n')) {
    key = wgetch (dialog);
    switch (key) {
    case 'E':        /* Exit */
    case 'e':
    case 'X':
    case 'x':
        delwin (dialog);
        free (buf);
        close (fd);
        return 0;
    case 'g':        /* First page */
    case KEY_HOME:
        if (!begin_reached) {
        begin_reached = 1;
        /* First page not in buffer? */
        if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
            endwin ();
            fprintf (stderr,
              "\nError moving file pointer in dialog_textbox().\n");
            exit (-1);
        }
        if (fpos > bytes_read) {    /* Yes, we have to read it in */
            if (lseek (fd, 0, SEEK_SET) == -1) {
            endwin ();
            fprintf (stderr, "\nError moving file pointer in "
                 "dialog_textbox().\n");
            exit (-1);
            }
            if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
            endwin ();
            fprintf (stderr,
                 "\nError reading file in dialog_textbox().\n");
            exit (-1);
            }
            buf[bytes_read] = '\0';
        }
        page = buf;
        print_page (text, height - 4, width - 2);
        print_position (dialog, height, width);
        wmove (dialog, cur_y, cur_x);    /* Restore cursor position */
        wrefresh (dialog);
        }
        break;
    case 'G':        /* Last page */
    case KEY_END:

        end_reached = 1;
        /* Last page not in buffer? */
        if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
        endwin ();
        fprintf (stderr,
              "\nError moving file pointer in dialog_textbox().\n");
        exit (-1);
        }
        if (fpos < file_size) {    /* Yes, we have to read it in */
        if (lseek (fd, -BUF_SIZE, SEEK_END) == -1) {
            endwin ();
            fprintf (stderr,
              "\nError moving file pointer in dialog_textbox().\n");
            exit (-1);
        }
        if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
            endwin ();
            fprintf (stderr,
                 "\nError reading file in dialog_textbox().\n");
            exit (-1);
        }
        buf[bytes_read] = '\0';
        }
        page = buf + bytes_read;
        back_lines (height - 4);
        print_page (text, height - 4, width - 2);
        print_position (dialog, height, width);
        wmove (dialog, cur_y, cur_x);    /* Restore cursor position */
        wrefresh (dialog);
        break;
    case 'K':        /* Previous line */
    case 'k':
    case KEY_UP:
        if (!begin_reached) {
        back_lines (page_length + 1);

        /* We don't call print_page() here but use scrolling to ensure
           faster screen update. However, 'end_reached' and
           'page_length' should still be updated, and 'page' should
           point to start of next page. This is done by calling
           get_line() in the following 'for' loop. */
        scrollok (text, TRUE);
        wscrl (text, -1);    /* Scroll text region down one line */
        scrollok (text, FALSE);
        page_length = 0;
        passed_end = 0;
        for (i = 0; i < height - 4; i++) {
            if (!i) {
            /* print first line of page */
            print_line (text, 0, width - 2);
            wnoutrefresh (text);
            } else
            /* Called to update 'end_reached' and 'page' */
            get_line ();
            if (!passed_end)
            page_length++;
            if (end_reached && !passed_end)
            passed_end = 1;
        }

        print_position (dialog, height, width);
        wmove (dialog, cur_y, cur_x);    /* Restore cursor position */
        wrefresh (dialog);
        }
        break;
    case 'B':        /* Previous page */
    case 'b':
    case KEY_PPAGE:
        if (begin_reached)
        break;
        back_lines (page_length + height - 4);
        print_page (text, height - 4, width - 2);
        print_position (dialog, height, width);
        wmove (dialog, cur_y, cur_x);
        wrefresh (dialog);
        break;
    case 'J':        /* Next line */
    case 'j':
    case KEY_DOWN:
        if (!end_reached) {
        begin_reached = 0;
        scrollok (text, TRUE);
        scroll (text);    /* Scroll text region up one line */
        scrollok (text, FALSE);
        print_line (text, height - 5, width - 2);
        wnoutrefresh (text);
        print_position (dialog, height, width);
        wmove (dialog, cur_y, cur_x);    /* Restore cursor position */
        wrefresh (dialog);
        }
        break;
    case KEY_NPAGE:        /* Next page */
    case ' ':
        if (end_reached)
        break;

        begin_reached = 0;
        print_page (text, height - 4, width - 2);
        print_position (dialog, height, width);
        wmove (dialog, cur_y, cur_x);
        wrefresh (dialog);
        break;
    case '0':        /* Beginning of line */
    case 'H':        /* Scroll left */
    case 'h':
    case KEY_LEFT:
        if (hscroll <= 0)
        break;

        if (key == '0')
        hscroll = 0;
        else
        hscroll--;
        /* Reprint current page to scroll horizontally */
        back_lines (page_length);
        print_page (text, height - 4, width - 2);
        wmove (dialog, cur_y, cur_x);
        wrefresh (dialog);
        break;
    case 'L':        /* Scroll right */
    case 'l':
    case KEY_RIGHT:
        if (hscroll >= MAX_LEN)
        break;
        hscroll++;
        /* Reprint current page to scroll horizontally */
        back_lines (page_length);
        print_page (text, height - 4, width - 2);
        wmove (dialog, cur_y, cur_x);
        wrefresh (dialog);
        break;
    case ESC:
        break;
    }
    }

    delwin (dialog);
    free (buf);
    close (fd);
    return -1;            /* ESC pressed */
}

/*
 * Go back 'n' lines in text file. Called by dialog_textbox().
 * 'page' will be updated to point to the desired line in 'buf'.
 */
static void
back_lines (int n)
{
    int i, fpos;

    begin_reached = 0;
    /* We have to distinguish between end_reached and !end_reached
       since at end of file, the line is not ended by a '\n'.
       The code inside 'if' basically does a '--page' to move one
       character backward so as to skip '\n' of the previous line */
    if (!end_reached) {
    /* Either beginning of buffer or beginning of file reached? */
    if (page == buf) {
        if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
        endwin ();
        fprintf (stderr, "\nError moving file pointer in "
             "back_lines().\n");
        exit (-1);
        }
        if (fpos > bytes_read) {    /* Not beginning of file yet */
        /* We've reached beginning of buffer, but not beginning of
           file yet, so read previous part of file into buffer.
           Note that we only move backward for BUF_SIZE/2 bytes,
           but not BUF_SIZE bytes to avoid re-reading again in
           print_page() later */
        /* Really possible to move backward BUF_SIZE/2 bytes? */
        if (fpos < BUF_SIZE / 2 + bytes_read) {
            /* No, move less then */
            if (lseek (fd, 0, SEEK_SET) == -1) {
            endwin ();
            fprintf (stderr, "\nError moving file pointer in "
                 "back_lines().\n");
            exit (-1);
            }
            page = buf + fpos - bytes_read;
        } else {    /* Move backward BUF_SIZE/2 bytes */
            if (lseek (fd, -(BUF_SIZE / 2 + bytes_read), SEEK_CUR)
            == -1) {
            endwin ();
            fprintf (stderr, "\nError moving file pointer "
                 "in back_lines().\n");
            exit (-1);
            }
            page = buf + BUF_SIZE / 2;
        }
        if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
            endwin ();
            fprintf (stderr, "\nError reading file in back_lines().\n");
            exit (-1);
        }
        buf[bytes_read] = '\0';
        } else {        /* Beginning of file reached */
        begin_reached = 1;
        return;
        }
    }
    if (*(--page) != '\n') {    /* '--page' here */
        /* Something's wrong... */
        endwin ();
        fprintf (stderr, "\nInternal error in back_lines().\n");
        exit (-1);
    }
    }
    /* Go back 'n' lines */
    for (i = 0; i < n; i++)
    do {
        if (page == buf) {
        if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
            endwin ();
            fprintf (stderr,
              "\nError moving file pointer in back_lines().\n");
            exit (-1);
        }
        if (fpos > bytes_read) {
            /* Really possible to move backward BUF_SIZE/2 bytes? */
            if (fpos < BUF_SIZE / 2 + bytes_read) {
            /* No, move less then */
            if (lseek (fd, 0, SEEK_SET) == -1) {
                endwin ();
                fprintf (stderr, "\nError moving file pointer "
                     "in back_lines().\n");
                exit (-1);
            }
            page = buf + fpos - bytes_read;
            } else {    /* Move backward BUF_SIZE/2 bytes */
            if (lseek (fd, -(BUF_SIZE / 2 + bytes_read),
                   SEEK_CUR) == -1) {
                endwin ();
                fprintf (stderr, "\nError moving file pointer"
                     " in back_lines().\n");
                exit (-1);
            }
            page = buf + BUF_SIZE / 2;
            }
            if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
            endwin ();
            fprintf (stderr, "\nError reading file in "
                 "back_lines().\n");
            exit (-1);
            }
            buf[bytes_read] = '\0';
        } else {    /* Beginning of file reached */
            begin_reached = 1;
            return;
        }
        }
    } while (*(--page) != '\n');
    page++;
}

/*
 * Print a new page of text. Called by dialog_textbox().
 */
static void
print_page (WINDOW * win, int height, int width)
{
    int i, passed_end = 0;

    page_length = 0;
    for (i = 0; i < height; i++) {
    print_line (win, i, width);
    if (!passed_end)
        page_length++;
    if (end_reached && !passed_end)
        passed_end = 1;
    }
    wnoutrefresh (win);
}

/*
 * Print a new line of text. Called by dialog_textbox() and print_page().
 */
static void
print_line (WINDOW * win, int row, int width)
{
    int y, x;
    char *line;

    line = get_line ();
    line += MIN (strlen (line), hscroll);    /* Scroll horizontally */
    wmove (win, row, 0);    /* move cursor to correct line */
    waddch (win, ' ');
    waddnstr (win, line, MIN (strlen (line), width - 2));

    getyx (win, y, x);
    /* Clear 'residue' of previous line */
#if OLD_NCURSES
    {
        int i;
        for (i = 0; i < width - x; i++)
        waddch (win, ' ');
    }
#else
    wclrtoeol(win);
#endif
}

/*
 * Return current line of text. Called by dialog_textbox() and print_line().
 * 'page' should point to start of current line before calling, and will be
 * updated to point to start of next line.
 */
static char *
get_line (void)
{
    int i = 0, fpos;
    static char line[MAX_LEN + 1];

    end_reached = 0;
    while (*page != '\n') {
    if (*page == '\0') {
        /* Either end of file or end of buffer reached */
        if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
        endwin ();
        fprintf (stderr, "\nError moving file pointer in "
             "get_line().\n");
        exit (-1);
        }
        if (fpos < file_size) {    /* Not end of file yet */
        /* We've reached end of buffer, but not end of file yet,
           so read next part of file into buffer */
        if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
            endwin ();
            fprintf (stderr, "\nError reading file in get_line().\n");
            exit (-1);
        }
        buf[bytes_read] = '\0';
        page = buf;
        } else {
        if (!end_reached)
            end_reached = 1;
        break;
        }
    } else if (i < MAX_LEN)
        line[i++] = *(page++);
    else {
        /* Truncate lines longer than MAX_LEN characters */
        if (i == MAX_LEN)
        line[i++] = '\0';
        page++;
    }
    }
    if (i <= MAX_LEN)
    line[i] = '\0';
    if (!end_reached)
    page++;            /* move pass '\n' */

    return line;
}

/*
 * Print current position
 */
static void
print_position (WINDOW * win, int height, int width)
{
    int fpos, percent;

    if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
    endwin ();
    fprintf (stderr, "\nError moving file pointer in print_position().\n");
    exit (-1);
    }
    wattrset (win, position_indicator_attr);
    wbkgdset (win, position_indicator_attr & A_COLOR);
    percent = !file_size ?
    100 : ((fpos - bytes_read + page - buf) * 100) / file_size;
    wmove (win, height - 3, width - 9);
    wprintw (win, "(%3d%%)", percent);
}
